Focus on Better Focus. Lens Align Pro Review & Tips:

Focus on Focus. A look at micro focus adjustments and the Lens Align Pro calibration system.

by Barry Howell:  Have you ever found a menu option on your camera that made you wonder, “What’s this”? I found such an option on my Nikon D300 called “AF Fine Tune.” My old-school curiosity sent me on a quest to discover its purpose, and how it could improve image quality. With a few quick Google searches, I found multiple forums and discussions about the importance of calibrating lenses to your DSLR camera bodies.

A recurring theme on the ProPhotoShow.com podcasts, and in other various articles, is how to make your images have more impact. There is no bigger buzz kill for photographers than capturing an image we think will be great, only to find that it’s a little soft. There are many variables we can control to ensure optimal sharpness: shutter speed, depth of field, steadying the camera, etc., and I always assumed that if I focused on the right spot, my images would be tack sharp. Guess what? That isn’t always the case, and I was determined to overcome the problem.

Before contacting Michael Tapes at RawWorkflow, I performed a very un-scientific, but effective test of my AF Fine tune option. I was photographing the MN State Boys Hockey Tournament at the Excel Energy Center, a venue that is well lit for television broadcasts. I very carefully focused my Tamron 300 2.8 lens on some helmets lined up on the boards. The scene had great contrast, I was using a monopod, and I figured could get this image dead on. I zoomed in at 100x on the LCD and it looked pretty good. I then went into the menu and made a +5 adjustment, took another shot, and upon inspection realized I had made it worse. Then, I made a -5 adjustment and the image improved noticeably. I knew then and there that I had to calibrate my optics.

Within a week I’d found such a tool; I obtained a Lens Align Pro Focus Calibration System. I invited several photographer friends for a focus calibration party at my studio and we embarked on a journey to make our gear perform better. In our group were five Nikon shooters and one Canon shooter. Between us, we probably had over $50,000 worth of bodies and glass waiting for a checkup. The results were at times sobering, but every lens, once calibrated, focused better than ever before. The calibration method involves the following steps; it took a little trial and error, but they were pretty easy to do reliably.

• Mount the Lens Align device on a tripod and precisely align it with the subject camera.
• Ensure proper lighting to allow a low ISO (200) and no shadows on the calibration device.
• Focus, defocus, and focus on the test setup, then capture a series of three or four images for evaluation.
• View images viewed at 100% in Photoshop with an Emboss filter effect.
• Calibrate to correct either front or back focus results.
• Shoot more test images as needed until fully calibrated.

This process only works for cameras that have the AF micro adjust feature. There is a full list of compatible cameras on the lensalign.com website, but Canon 50D and above, and Nikon D300 and above DSLR cameras all have this feature. If you are striving to be a professional photographer and shooting a Canon Rebel, or a Nikon D5000, this might be a sign it’s time to upgrade.

The following two files show a before and after calibration on a Nikkor 70-210 2.8 VR lens on a Nikon D300. As you can see, the lens was front focusing badly. The DOF chart indicates that this focal length at the test distance (16 ft.) at 2.8 will have a DOF of only 3.1 in. If your focus is off by an inch or more, your “sharpness” is compromised by about 30%. I was originally taught many years ago that depth of field started at the point of focus, and carried back. What we now know is that the depth of field is more equally divided, but will always favor carrying beyond the point of focus greater than it will in front of your plane of focus.

Your camera will record each calibrated adjustment, to the specific lens, and it will remember the adjustment every time you mount the lens on the camera. My D300 stores the information for up to 12 lenses; it knows what lens is mounted when calibration begins. You will need to test and calibrate every lens to every focus-adjustable DSLR you own.

Here are some tips that will make your life easier when you calibrate.

• Follow the instructions carefully, and pay close attention to the correct settings.
• The directions stress precise alignment, and it really is very important to do it right (shine a small flashlight thru viewfinder when rear sighting)
• Turn off VR and use an electronic cable release or self-timer (highly recommended).
• Observe how long it takes your camera to “settle” when viewing the target thru the lens once you remove your hand from the lens.
• Eliminate variables and be consistent in every step.
• Use the nifty little magnets to record distance, adjustments, etc.
• Create a folder on your computer for each lens tested (for quick reference later).
• Create a Photoshop Action to create the Emboss effect, and set to 100%.
• Calibrate zooms either at the zoom setting you typically use, or the max end of the zoom range.
• Test with and without filters.

My Conclusion:

While we can sometimes improve and correct sharpness issues in post production, it is far better to go “old school” and get it right the first time. If you are serious about optimal performance, I think this system is money well spent to calibrate your gear for maximum sharpness. The unit we tested sells for $179, but they sell a few different versions, including a long ruler for wider glass. You can find the tool on the Lens Align website. Also be sure to check the quality and optical integrity of your filters. We discovered that one lens that seemed ready to be sent back to Nikon for softness problems simply had a bad filter.  I also discovered that my 300 2.8 lens sharpness was being compromised by a simple 49mm drop in filter back near the mount.

For those wanting to spend a bit less I also found several FREE tools for calibrating lenses. Here is a good source for some alternative methods. While I’m sure these methods work, I felt they required more “trial & error” both in alignment, and in determining what calibration is needed.  These alternative methods mention the need to square up the camera to the monitor (in one case which utilizes a computer monitor which some may not be able to move back far enough from to test longer lenses).

I found the specific, and visual feedback of the lensalign device makes certain things are aligned perfectly, and the results are easy to understand.  No trial & error here, just obvious front or back focus issues.  Based on what we invest in our camera gear, I don’t mind spending a little money to ensure my lenses are always performing properly, but for those who want to do a bit more footwork take a look at the freebies linked above.